In view of the common problems in the middle and later stages of steam-assisted gravity drainage（SAGD）development with dual-horizontal wells，such as insufficient formation energy，low oil discharge capacity and oil-steam ratio，and serious heat loss，the technology of multi-media enhancement to improve development effects was put forward. The key mechanism was revealed，and the main injection parameters were optimized by combining laboratory experiments and numerical simulation. The results show that the injection of multi-media can reduce the viscosity，improve the shapes of steam chambers，increase the gravity oil discharge capacity，alleviate the heat loss，and save the steam in the middle and later stages of SAGD development. The solvents are easier to dissolve and reduce viscosity when the steam chambers extend to the tops of the reservoirs，and stopping the injection of solvents can improve the recovery rates when the steam chambers stop the lateral expansion；injection timings，methods，and amounts of non-condensate methane have a significant influence on the final oil-steam ratio. Compared with that of pure SAGD，the average daily oil production of SAGD enhanced by multiple media increases by 3.9 t/d. The oil-steam ratio increases by 0.093，and the daily steam injection decreases by 6.7 t/d. The technology has been implemented for three months，and the input-output ratio is 1∶4.